Self-lubricating be a ring materials are already known. In their most common form they consist of a porous sintered layer of tin or lead-bronze alloys applied to a steel backing. Mixtures of fluoropolymers with various fillers are worked into the porous sintered layer in such a way that they form a layer of from 10 to 30 .mu.m on the sintered backing.
A method for producing self-lubricating bearings is described in DE-PS-1 132 710. In this method a paste produced from a PTFE dispersion (polytetrafluoroethylene dispersion) and fillers is inserted under pressure into cavities in a porous bronze layer and the metal is then sintered. DE-PS-1 132 710 also describes the production of a PTFE filler paste. The fillers are mixed with a PTFE dispersion in a concentration of between 5 and 60%, whereupon, with the aid of a salt which forms an insoluble compound with the dispersion-stabilising ionic wetting agent, coagulation of the PTFE then occurs with homogeneous inclusion of the added fillers. It should be mentioned that in this method volatilizable organic solvents, e.g. toluene, and optionally additionally a surface-active substance, such as ethylphenylpolyglycol ether or a fatty alkyl sulphonate, may be used. The surface-active substances are used for the purpose of better wetting and thus more homogeneous incorporation of the fillers. The organic solvents are used in order to achieve the desired consistency of the paste, which enables the achievement of the necessary small covering layer thicknesses of from 10 to 30 .mu.m on the finished part.
In heavily loaded plain bearings cavities often arise through cavitation, which cavities explode again after a short time, thereby releasing energy. This released energy results in local destruction of the material, whereby the service life of the components made of the material is considerably reduced.